This invention relates to a catheter assembly which includes a hollow introducer needle, a flexible, fenestrated dilator slidably mounted over the needle, a flexible sheath slidably mounted over the dilator and means for viewing an early occurring blood or other biological liquid flashback, indicative of proper placement of the needle and/or dilator in a biological organism. The invention also relates to such an assembly wherein provision is made for monitoring blood pressure, sampling blood and for liquid infusion as soon as the needle penetrates a blood vessel prior to placement of the dilator and sheath therein without the necessity of changing connections to the assembly.
Broadly speaking, catheter assemblies having a hollow introducer needle, a flexible dilator slidably mounted over the needle and a sheath slidably mounted over the dilator for successive insertion into a blood vessel or other biological liquid containing region of a human or animal body have long been known and used in the prior art. A difficulty that has been encountered with all known prior art catheter assemblies of this type is that, in order to use blood pressure monitoring equipment to determine with a high degree of certainty whether the needle has been properly inserted into a vein, as opposed to an artery, or vice versa, prior to placement of the dilator and sheath into the blood vessel, certain elements of the assembly must first be disconnected in order to connect blood pressure monitoring equipment. Such changing of connections on the assembly is time consuming and is often an awkward process. Yet such a process is essential in order to determine with certainty the proper placement of the needle prior to placement of the dilator and sheath.
The difficulty exists because of the lack of any provision for communication of blood from the vessel penetrated by the needle with a cavity within a hub of the sheath for introduction into a side port of the hub, to which monitoring equipment is or can be attached, prior to placement of the sheath in the vessel and removal of the needle and dilator from the sheath. In such prior art assemblies blood flows from the vessel penetrated by the needle into either a syringe or a guidewire housing connected behind the sheath hub so long as the needle is in an advanced operative position. Consequently, with the needle in such an operative position, there is no blood flow communication with an interior cavity of the sheath hub or with a hub sideport. In the case of a guidewire housing connected behind the sheath hub, the housing must first be disconnected from the hub, assuming it can be disconnected, which is not always possible, in order to connect monitoring equipment at the rear of the hub. In such a case, unsanitary blood spillage is likely to occur. In the case of a syringe connected at the rear of the hub, the syringe must first be removed in order to connect monitoring equipment, again, with the likelihood of blood spillage. Even with more recently available blood containing, guidewire introducing syringes and bulbs, transducer tubing must be connected and, then, disconnected prior to guidewire advancement.
By means of our invention, these and other difficulties encountered using such prior art catheter assemblies are substantially eliminated.
It is an object of our invention to provide a catheter assembly having an introducer needle, fenestrated dilator and sheath which provides for communication of blood from a vessel being penetrated by the needle to a side port of the hub prior to insertion of the dilator and sheath into the blood vessel.
It is a further object of our invention to provide such a catheter assembly with provision for observing an early occurring blood flashback through a transparent or translucent body of a sheath and, in certain cases, through an underlying transparent or translucent dilator, near a distal end of the assembly, well within the field of vision of an operator who is concentrating on the region of needle penetration.
In accordance with these objects, we provide a catheter assembly which includes an elongated, hollow introducer needle adapted for insertion into a biological liquid containing region of a patient. A flexible, hollow tubular dilator defining at least one fenestration therein is also included, the dilator being adapted for slidable disposition over the needle. A flexible, hollow tubular sheath is provided which is adapted for slidable disposition over the dilator. The sheath includes at least one sideport which communicates with a lumen of the sheath. A means for conducting a biological liquid from the patient, as a result of insertion of the needle into the sideport through the first dilator fenestration is also provided.